Phenolic composition and antioxidant activity of aqueous infusions from Capparis spinosa L. and Crithmum maritimum L. before and after submission to a two-step in vitro digestion model.

This study investigated the phenolic composition and antioxidant activities of aqueous infusions from wild-grown caper (Capparis spinosa L.) and sea fennel (Crithmum maritimum L.) from the Dalmatia region (Croatia) before and after their submission to an in vitro digestion process. HPLC/UV-vis-DAD/ESI-MS analysis of the caper infusion identified rutin, kaempferol 3-O-rutinoside, and isorhamnetin 3-O-rutinoside as dominant flavonoids in the matrix together with a series of cinnamoylquinic acid derivatives, whereas in the sea fennel aqueous infusion chlorogenic acid (5-caffeoylquinic acid), its isomers, and higher derivatives were identified as almost the sole class of phenolics. Both infusions exhibited good and dose-dependent antioxidant activity before in vitro digestion by the DPPH method, the ß-carotene bleaching method, and copper-induced oxidation of human LDL. The amount of total phenolics (Folin-Ciocalteu assay) strongly decreased in digested samples (from 3.0 and 2.2% in caper and sea fennel infusions, respectively, to <1.0%), as did their antioxidant activity as measured by the three aforesaid methods. The results showed that the majority of phenolic compounds detected in both infusions are not stable under applied simulated gastrointestinal conditions and that the stability of these secondary metabolites strongly depends on the nature of the corresponding matrix.

On the surface properties of oleate micelles and oleic acid/oleate vesicles studied by spin labeling.

Dilute aqueous systems composed of sodium oleate micelles and sodium oleate/oleic acid vesicles were investigated as a function of pH by electron spin resonance spectroscopy with TEMPO-stearate TEMPO-stearamide as well as with a positively charged water soluble spin label, TEMPO-choline. The dynamics of the three TEMPO-spin labels were found to be sensitive to changes in the interfacial region of the aggregates as a function of pH. The results obtained are consistent with the formation of a hydrogen bond network (RCOO(-)↔HOOCR) at the surface of the sodium oleate/oleic acid system in the course of the transformation of micelles into the closed bilayers (vesicles). Vesicles formation below pH 10 was determined independently with a spin labeled glucose derivative.

An ESR characterization of micelles and vesicles formed in aqueous decanoic acid/sodium decanoate systems using different spin labels.

Aqueous decanoic acid/sodium decanaote systems were studied as a function of pH and concentration, up to 0.3 M decanoic acid/sodium decanoate, by electron spin resonance (ESR) spectroscopy using three different amphiphilic spin labels. The distribution of the spin labels between vesicles and micelles as well as their dynamic properties were determined by quantitative analysis of the ESR spectra using two novel simulation software packages. Rotational correlation time of the labels in micelles was found to increase with decreasing pH, with substantial increase in the region where vesicles were formed (7.8